Whenever I tell people what I’m studying in grad school, they seem pleased for a moment, but it doesn’t take long for them to look totally perplexed. It’s as if I told them I study gopher economies.
“Medical Physics? What does medicine need physicists for?”
The answer is: a lot of things. And it’s the reason I feel confident about having earned a bachelor’s in Physics at all.
As an undergrad, one branch of Physics stood out to me above all the rest: particle physics. Where else could you send an atom to 99.9999% the speed of light, around a miles long underground track, and collide it with an identical atom moving that fast in the opposite direction? How can you even see any of the resulting explosion of particles that are created and destroyed in a matter of picoseconds? Maybe it was the insanity of it all that kept me entranced. But approaching graduation, I had to decide how I was going to put my knowledge of the field to practical use, and it wasn’t as easy as I had imagined. Sure there are particle accelerator labs to work for – Fermilab and Brookhaven National Lab – but those and a couple more are all we have in the US. For a time I thought I would end up a professor, able to work at a great number of academic institutions, but I was dismayed after hearing the size of the applicant pool for a single faculty position at my university. Luckily for me, I learned about a third option.
Medical Physics is all about using physics, mostly radiation and particle physics, for clinical purposes. The field is separated into four main branches: Radiation Therapy, Diagnostic Imaging, Nuclear Medicine, and Health Physics, each using different physics principles to aid patient treatment and improve outcomes.
Radiation Therapy uses linear accelerators to create beams of particles which can penetrate into the body and target cancer tumors that surgery can’t remove. The name of the game is depositing enough energy to kill cancerous cells, while protecting the important organs around it.
Diagnostic Imaging physicists work hand in hand with radiologists to provide doctors with clear transmission images of patients. They have a wide variety of technologies at their disposal, including MRI, CT, ultrasound, and conventional x-ray imagers. While physicians can’t see into patients to find out what’s wrong, physics has plenty of work-arounds.
Nuclear Medicine cleverly designs safely radioactive tracer compounds that can absorb into organs in the body for a sense of how well they are functioning. PET and SPECT detectors see the radiation coming from inside the patient and can map the organ systems based on radioactivity. Certain cancers can also be treated with ingested radioactive material, specifically absorbed by the part of the body that the cancer resides in.
The last of the four, Health Physics, deals with the safety of the public and everyone inside hospitals that use radiation. Since x-rays can go through bones, they can go through walls as well. Radiation safety officers ensure healthcare workers and hospital guests are not subject to dangerous levels of radiation leaking from accelerators and radioactive material inside treatment rooms.
While radiation has been useful in medicine ever since the early 20th century, computerization has allowed its practicality to explode. Each decade, novel treatment techniques are being devised that allow for finer tumor control, and better survivability. Artificial intelligence is just starting to find a use in treatment planning, and will probably have a lot of advancement opportunities for the field.
So, how does one become a medical physicist? The typical pathway is to get a bachelor’s in Physics or a related field, such as Nuclear Engineering, and go to grad school in a CAMPEP accredited program. Many clinical positions are open to master’s recipients, but PhD programs also exist for those who want to pursue research in the field. After graduating, medical physicists participate in a 2 or 3 year residency, similar to doctors immediately after med school. This teaches the clinical aspects of the job, and ensures physicists are ready to be entrusted with the lives of patients. After residency, you’re set to work for any of the thousands of hospitals in the country who use radiation to better the lives of people in their communities!
For me and a relatively small minority of healthcare professionals, medical physics is the perfect way to apply my love of physics to produce tangible benefits in society. I only wish I had known about it as a career path sooner. If you want to learn more about the field, visit AAPM.org, or ask a physicist in a cancer center near you if you can shadow them, or simply tour their facilities.